1. Field of the Invention
The present invention relates to signal processing apparatuses for solid-state imaging devices, signal processing methods, and imaging systems. More particularly, the present invention relates to a signal processing apparatus capable of correcting color mixture in the pixel area of a solid-state imaging device, a signal processing method in the signal processing apparatus, and an imaging system including the signal processing apparatus.
2. Description of the Related Art
Solid-state imaging devices, such as charge coupled device (CCD) image sensors and complementary metal oxide semiconductor (CMOS) image sensors, have structures in which condenser microlenses are layered on color separation filters that are layered on pixel cells including photoelectric transducers.
In color solid-state imaging devices having the above structures, the distances between the pixel areas and the microlenses are increased because of the color filters located between the pixel areas and the microlenses. The distance between the pixels, that is, the pixel pitch decreases with decreasing size of the pixel cells involved in an increase in number of the pixels. Accordingly, light transmitting through the color filter for a certain pixel cell can enter neighboring pixel cells to cause a problem of color mixture.
In order to resolve the problem of the color mixture caused by the decreased size of the pixel cells, in solid-state imaging devices in related art in which the pixels having the three primary colors including red (R), green (G), and blue (B) are arranged in a checker pattern, signal components corresponding to a certain ratio are subtracted from the signal of a pixel having a given color (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-135206). The signal components corresponding to the certain ratio are calculated from the signals of pixels that are adjacent to the pixel having the given color and that have a color other than the given color.